Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure

Andreea Loredana Cretu, Lucia Garritano, Marco Schioppa

American Journal of Educational Research

Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure

Andreea Loredana Cretu1, Lucia Garritano2,, Marco Schioppa2

1Neural Control of Movement Lab, Department of Health Sciences and Technology, ETH Zurich, Switzerland

2Department of Physics, University of Calabria, Italy


The school is the place where we learn to combine thinking with doing. This paper describes the experimental activity conducted at the high school Enrico Fermi of Catanzaro Lido (Italy), within the Extreme Energy Events (EEE) Project. The Project is supported by the “Ministero dell’Istruzione, Università e Ricerca (MIUR)”, “Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi”, “Istituto Nazionale di Fisica Nucleare (INFN)” and the European Organization for Nuclear Research (CERN). The main scientific goals of this project are the investigation of the properties of the muon flux. The Project is also characterized by a strong educational and outreach aspect. The telescopes are located in Italian high schools and managed by teams of students and teachers who have also attended in their construction at CERN. The purpose of this article is to underline the educational value of the project. The activity, deriving from experiential learning, indicates that performing research in an advanced field of investigation can be a way to improve the learning of scientific topics. This paper describes how the teaching activity is conducted and describes the methodology to monitor the muon flux as a function of time: results show the negative correlation of muon flux with the variation of the local pressure. By combining our measurements with observations from two other solar imaging instruments we were able to look for unusual variation of the flux, such as solar flares. This approach has allowed students to learn not only a new physics topics but also a team-working methodology and benefit from experiential learning which will be useful in their future work.

Cite this article:

  • Andreea Loredana Cretu, Lucia Garritano, Marco Schioppa. Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure. American Journal of Educational Research. Vol. 4, No. 16, 2016, pp 1164-1173. http://pubs.sciepub.com/education/4/16/7
  • Cretu, Andreea Loredana, Lucia Garritano, and Marco Schioppa. "Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure." American Journal of Educational Research 4.16 (2016): 1164-1173.
  • Cretu, A. L. , Garritano, L. , & Schioppa, M. (2016). Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure. American Journal of Educational Research, 4(16), 1164-1173.
  • Cretu, Andreea Loredana, Lucia Garritano, and Marco Schioppa. "Experiential Learning and Physics: The Correlation of Muon Flux with Variations in Local Pressure." American Journal of Educational Research 4, no. 16 (2016): 1164-1173.

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At a glance: Figures

1. Introduction

This article describes the use of experiential learning concepts in a complex multi-center project. Although the principles of learning through experience are not new, only in the past few years, more and more schools and universities started to understand its importance and apply it to help students gain real-world experience in different fields.

The EEE (Extreme Energy Events) Project has started more than ten years ago with the construction and installation of a set of cosmic ray telescopes in different Italian high schools [1, 2]. The map of the distribution of the telescopes is shown in Figure 1.

The aim of this project is two-fold. First, it serves as an educational instrument for students. They are involved, together with their teachers and tutors in all the research steps, from the construction of telescopes to data acquisition and analysis. Second, it is a scientific instrument for physicists allowing high-level research to be conducted in different locations across the country [3]. Each telescope is made by three Multigap Resistive Plate Chambers (MRPCs) allowing the precise reconstruction of the orientation and arrival time of cosmic ray secondary muons [4]. A MRPC consists of resistive surfaces with multiple gas-gaps [5, 6]. This is a gaseous detector that uses the principles of gas ionization. It is very important to determine the efficiency of MRPC for a proper functioning of the detector itself. The students were periodically involved in making efficiency tests in order to check that everything is working correctly [7]. The characteristics of the detector provide a manifold approach to the study of cosmic rays. It is possible to study very high energy cosmic ray showers by means of coincidences between telescopes located all over Italy. The first detection of coincidences among different telescopes by means of the EEE network was performed at L’Aquila, where the two telescopes of the site were positioned at the closest distance among the telescopes of the network [8]. Later on, coincidences were detected also at the Cagliari site, where also two muon telescopes are less than a km far away from each other, and the relative preliminary results have been reported elsewhere [9]. Under these circumstances, the time correlation is made possible using a GPS unit for each telescope, providing a precision time stamp event by event [10].

All the raw data from the running telescopes are automatically transferred at the CNAF (Centro Nazionale Analisi Fotogrammi) in Bologna, the biggest Italian storage and computing center managed by INFN [11]. The data are first reconstructed and all the outputs, together with the raw data are put on a web page (Figure 2). Researchers and students can afterwards freely access the data to perform their own data monitoring and analysis [12].

2. Metodology

Most teachers recognized and understand the important role of experience in the learning process. The renewal of the scientific curriculum happens not only through the use of technology, but also through the use new teaching methods. During this project we have carefully taken into account the IBSE methodology (Inquiry Based Science Education), which allows the exploration of reality through observation, discussion, conducting investigation, data collection and data processing. Noting the limitations of the classic frontal lessons, we acknowledge the value of focusing on the student and using experiential learning, namely "learning through reflection on doing" [13] Learning from experience is a methodology that promotes experimentation, discovery, and reflection on the practice as well as discussion and exchange of ideas in teams. Important to realize, we conducted the teaching not only in a physical dimension but more importantly, we created a space by integrating two areas: the physical and above all mental. In this way, the laboratory activity makes protagonist the student because it promotes discussion, comparison and reasoning [14]. The goal is to "produce thought starting from the action", so that the laboratory will become a significant component of learning and not just a place for its application [15].

Figure 1. The map of distribution of the EEE telescopes on the Italian territory (plus 2 at CERN). The numbers inside the stars indicate the presence of more than one EEE site in the same town
Figure 2. Web page which students can access to perform their own data monitoring and analysis

In this activity our reference point is Kolb's model on experiential learning [16]. Kolb developed the theory of experiential learning in 1984 and we use it now as a useful model for developing and adapting our teaching practices. His model includes "The Kolb Cycle", "The Learning Cycle" or "The Experiential Learning Cycle" being typically represented by a four stage learning cycle. (Figure 3).

This approach engages all students through feedback, reflection, and the application of the ideas and skills to new situations. The students have the opportunity to learn from their experiences and mistakes. In the model it can be seen how experience is transformed into ideas and concepts with the help of reflection. The ideas can then be used for active experimentation and evolution of new experiences. The student must make the link between the theory and practice by planning and reflecting always in relation to the learned theory. The methodology is also characterized by a strong educational and outreach aspect since the experiments are managed by students and teachers who operate effectively in a team.

2.1. Management and Organization

Students and teachers have participated in the activity using a management of teamwork according to scheme shown in Figure 4.

The organization of the teamwork is shown in Figure 5.

The organization employed in this project can be characterized as a “learning organization” which engages students and teachers in one team. In a learning organization, everything is performed in a team rather than individually, in order to reach a common goal. The leader is someone who provides guidance, instruction, direction and leadership to a group of other students (the team) for the purpose of achieving a final result and maximize efficiency. The leader's role is to coordinate activities and colleagues, rather than by providing expert information. Students are not completely left to teach themselves, however, the teacher assumes the role of guide, facilitates the learning process and shares responsibility. Why is it important then to organize the work activities in groups? The group has benefits for organizational purposes because it allows:

• distribution of work

• management and control of work

• problem solving and decision-taking

• information processing

• idea collection

• increasing commitment and involvement

Even if other teaching methods focus on group activities because they can offer more productivity, creativity and motivation than individual work, they tend to ignore the fact that students need to maintain a level of individuality in order to be able to face modern society. The experiential learning focuses on group activities while still allowing the students to:

• establish a role for themself

• share experience for a common purpose

• gain help and support to carry out project objectives

In our project, the students organize themselves in groups every day and work for together for the data acquisition, e-logbook writing and data analysis.

3. Experimental Setup and Data Analysis

The monitoring of the detector (Figure 6) and the control of data quality are important to validate the analysis of the data and the scientific results. The telescopes have been designed for continuous operation. This characteristic makes the EEE array a tool for monitoring the secondary cosmic-ray flux, that is usually affected by periodic and non-periodic variations. In fact, the high sensitivity of the EEE telescopes allows to detect small fluctuations of the local muon flux, due, for example, to meteorological effects (i.e. changes in the atmospheric pressure and temperature) or to daily variation effects related to solar phenomena.

Figure 6. The MRPCs detector (left) and the electronic data acquisition system (right)

The system is checked once a day. All the parameters related to the state of data collection are recorded and monitored using the Data Quality Monitor (DQM). The DQM system provides information on the data quality with control distributions and, above all, the rate of events and tracks the reconstructed muons. The system is also equipped with a weather station, so we also record environmental variables which might have an influence on the data (Figure 7).

These data allow us to observe important fluctuations of temperature and pressure and identify suitable periods to extract barometric corrections. The data are available in .root format [17], or in .csv (Comma Separated Value) so the data downloaded in this format are processed using standard spreadsheets (Excel/Calc).We have analyzed enormous amounts of events. This allowed us to study the relation between the variations in the muon flux and changes in atmospheric pressure. When analyzing variations in cosmic ray intensity using ground-based detectors, atmospheric effects of secondary particles on the flux cannot be ignored. The barometric effect is experimentally determined by the following equation:


where is the normalized deviation of the cosmic ray intensity related with the pressure effect, is the atmospheric pressure deviation and β is the barometric coefficient [18]. The barometric coefficient depends on many factors such as the nature of the secondary component and the altitude where the observation is performed [19]. The telescope of Catanzaro is located approximately 20 m of altitude above the sea level. Due to the effect of the absorption in the atmosphere, the value of β is negative, indicating an anti-correlation between the observed flux and the atmospheric pressure. When studying possible variations of the cosmic-ray flux, it is necessary to correct the measured event rate of the telescopes for the barometric effect. It can be done by looking for the anti-correlation between the event rate and the atmospheric pressure.

Our analyzes were done by selecting certain periods of the recorded data because it’s important to identify time periods with low solar activity. We have analyzed the variations in pressure and muons flux after identifying periods when no significant geomagnetic and solar disturbances were present. The data were divided into runs with up to 50,000 events. They were collected and transmitted by the CNAF server-based event-by-event: each event corresponds to the passage of a particle through the three chambers of the detector. The data are conveniently processed to enable the study of the different properties of cosmic radiation. Binary files are important to view and extract the necessary information. To calculate our correlations, the variables which are relevant for us are: the "BinStart" (i.e. the start time), the "RateTrackEvents" (i.e. the rate of the tracks reconstructed in Hz) and "Pressure" (i.e. the atmospheric pressure measured in mbar) (Figure 8).

4. Results and Discussions

The first step was to plot "RateTrackEvents" and "Pressure" in function of the time. Since events are recorded every minute, it is more convenient to merge the data into larger time-bins and to calculate the average. We extracted data averaged every 30 minutes, to construct a more readable plot. Plotting the pressure in function of time, as shown in Figure 9, indicates that the trend of the pressure, in the period of time considered, is characterized by considerable variations (about 10 mbar).

Figure 9. Pressure variation as a function of time for a period of 11 days (from 21/11/2015 to 25/11/2015)

The plot of muons rate reported in the same period is shown in Figure 10.

Examination of the two plots shows a negative correlation between the flux of muons and atmospheric pressure: when the pressure decreases the rate is on average higher, while it is lower when the pressure increases. This negative correlation can be highlighted in the plot shown in Figure 11.

The anti-correlation between the flux of cosmic rays and the pressure is shown in Figure 12 where we proceed to linear interpolation of the data, expressed in the equation (1).

The slope m of the fit line shows the anti-correlation between the muon flux and atmospheric pressure. We use this slope to determine the barometric coefficient (expressed in % / mbar):


In the specific case, with m = -0.0648, and the average value of rate = 27, 60 Hz, we get the value of β = -0.2348 (% / mbar). We use this value of β/100 for data correction because of barometric effect:


where is the variation of atmospheric pressure compared to the average value evaluated in the range of analysis.

Figure 10. Muons rate as a function of time in days for 21/11/2015 to 25/11/2015
Figure 11. Muons rate and atmospheric pressure: variation as a function of time in days for 21/11/2015 to 25/11/2015
Figure 12. Scatter plot showing the track rate as a function of pressure
Figure 13. Muons rate and atmospheric pressure: variation as a function of time in days for 12/03/2016 to 16/03/2016

This negative correlation was detected in other periods of time as well. Figure 13 and Figure 14 show the correlation observed in March and April 2016.

This study of muon flux variation was always combined with the observation of the data detected by "Oulu Neutron Monitor Station" [20] and "TESIS" [21]. This allows the identification of interesting phenomena in correspondence of events that cause variations in the cosmic rays flux, such as decreases the Forbush. The measurements detected by Neutron Monitor, compared to those of the muon component are affected more strongly by the effects of solar activity, because of their connection with lower energies. This allowed us to select low solar activity time periods. Based on our observations it is evident that there is a significant drop of muon flux during higher pressure time periods while higher counting rate is seen in low pressure periods. This means that the muon flux is modulated by the atmospheric pressure. The barometric effect, more specifically, the effect of atmospheric pressure can therefore cause important changes in the frequency rate of muons [22].

Figure 14. Muons rate, and atmospheric pressure: variation as a function of time in days for 20/04/2016 to 26/04/2016

5. Scientific and Educational Value of All Activity

The activity has been welcomed and appreciated by all the students. As Kolb states, “learning is the process whereby knowledge is created through the transformation of experience”, therefore, performing complex experiments using this framework has a lot of benefits for the students. Working in a team has allowed the students to apply problem solving procedures and share tasks responsibilities with the final goal of achieving effective learning by passing through all the four stages of the learning cycle. This approach has created an environment that resulted beneficial for both learning and strengthening of interpersonal relations in the group. Consequently, this kind of experience involved not only a simple collaboration among the students but an "experiential learning". All activities have been organized in order to constitute a valid and mutual integration with the theory. It was not only a moment of experimental verification of what the students have learned in theory, but also a basic tool to derive laws, principles, theoretical models starting from this experience. The use of the methodology ensures greater involvement and awareness of students, while allowing everyone to make an effective contribution. The purpose is precisely "learning-by-doing-thinking". This kind of experience has also an educational value because it creates in the students greater self-esteem that comes from perceiving their progress in the activity. At the same time, gives students and teachers the opportunity to:

• reflect on the learning process

• become aware of the personal potential and limitations

• become more aware of learning strategies

• give room for creativity and intuition.

The main training objective is to address the role of science and technology through team-working and mutual cooperation with the continuous exchange of ideas and comparison. This educational activity allows students to gain knowledge in different fields , in particular:

Physics: particle's physic, detector's physics, astrophysics

Electronics: electrical and electronic components

Technique of materials: mechanical devices and materials

Computer Science: management of the acquisition software and data analysis, information management apparatus, implementation of remote control systems.

This kind of activity isn't only a simple teamwork but a cooperative learning. The teamwork consists only to cooperate to a common aim. The cooperative learning is, instead, a way focus on learning each other, but above all one for the other.

This educational activity, allowed us to obtain important pedagogic and scientific results.

The used approach stimulated students curiosity with respect to a tough matter, such as the investigation of the physics of cosmic rays and particle detectors, creating a challenging and cooperative environment, enabling knowledge sharing and determining a reinforced self-esteem of the students and an increased ability to face complexity by a step by step process.

6. Conclusions

It was a team work. The way in which students worked in teams and the discussions with them, have shown a real assimilation of the new concepts and an improvement resulting in scientific learning. As already outlined in the Introduction, an important part of the EEE Project is the possibility to be a very effective method to communicate the meaning of the scientific research to students. This was one of the reasons why it was decided to locate the EEE telescopes in high schools and to have students help “hands on” in the assembling, testing and monitoring of the detectors and in data taking and analysis. Moreover, "younger students" work in close contact with more experienced ones, this means that acquired skills are transmitted in the most natural way. Beyond its interesting scientific goals, the peculiarity of the EEE project lies in the fact that most of the activities related to the experiment are carried out by Italian high-school students and teachers, working in close contact with the professors, researchers and technicians of the Universities, INFN and Centro Fermi. From the point of view of scientific communication and outreach activities, this is a very important added value to the EEE Project.


We thank the students and the director of the High School "E. Fermi" of Catanzaro Lido, who accepted the task with enthusiasm and involvement. At the same time we thank the Centro Fermi and the entire EEE Collaboration which made this work possible.


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